A variety of gaseous species may be contained in cigarette smoke, such as polynuclear aromatic hydrocarbons (PAHs), heterocyclic compounds, hydrogen cyanide (HCN), nitric oxides (NOx) and carbon monoxide (CO). Conventional techniques, such as normal dilution, filtration, or selective filtration are not completely satisfactory for reducing such constituents in mainstream cigarette smoke.
Despite the developments to date, there is interest in improved and more efficient methods and compositions for reducing the amount of carbon monoxide in the mainstream smoke of a cigarette during smoking. Preferably, it should be possible to catalyze and/or oxidize carbon monoxide not only in the filter region of the cigarette but also along the entire length of the cigarette during smoking.